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<meta name="description" content="Custom policy for collapsing and expanding subtrees, different than TreeExpanderButton."/> 
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<title>Different Criteria for Hiding "Children" of Collapsed Nodes</title>
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          <h1 class="mb-0 p-1 ">GoJS</h1>
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    <!-- Start of GoJS sample code -->
    
    <script src="../release/go.js"></script>
    <div class="p-4 w-full">
    <script id="code">
    function init() {
      var $ = go.GraphObject.make;

      myDiagram =
        $(go.Diagram, "myDiagramDiv",
          {
            padding: 10,
            layout: $(go.LayeredDigraphLayout,
              { direction: 90, layeringOption: go.LayeredDigraphLayout.LayerLongestPathSource }),
            "undoManager.isEnabled": true
          });

      myDiagram.nodeTemplate =
        $(go.Node, go.Panel.Vertical,
          { portId: "", fromLinkable: true, toLinkable: true },
          new go.Binding("visible"),
          $(go.Panel, go.Panel.Auto,
            $(go.Shape,
              { fill: "white", minSize: new go.Size(30, 30), strokeWidth: 0 },
              { cursor: "pointer" },  // indicate that linking may start here
              new go.Binding("fill", "color")),
            $(go.TextBlock,
              { margin: 2 },
              { fromLinkable: false, toLinkable: false },  // don't start drawing a link from the text
              new go.Binding("text", "key"))),
          $("Button",  // a replacement for "TreeExpanderButton" that works for non-tree-structured graphs
            // assume initially not visible because there are no links coming out
            { visible: false },
            // bind the button visibility to whether it's not a leaf node
            new go.Binding("visible", "isTreeLeaf",
              function(leaf) { return !leaf; })
              .ofObject(),
            $(go.Shape,
              {
                name: "ButtonIcon",
                figure: "MinusLine",
                desiredSize: new go.Size(6, 6)
              },
              new go.Binding("figure", "isCollapsed",  // data.isCollapsed remembers "collapsed" or "expanded"
                function(collapsed) { return collapsed ? "PlusLine" : "MinusLine"; })),
            {
              click: function(e, obj) {
                e.diagram.startTransaction();
                var node = obj.part;
                if (node.data.isCollapsed) {
                  expandFrom(node, node);
                } else {
                  collapseFrom(node, node);
                }
                e.diagram.commitTransaction("toggled visibility of dependencies");
              }
            })
        );

      function collapseFrom(node, start) {
        if (node.data.isCollapsed) return;
        node.diagram.model.setDataProperty(node.data, "isCollapsed", true);
        if (node !== start) node.diagram.model.setDataProperty(node.data, "visible", false);
        node.findNodesOutOf().each(collapseFrom);
      }

      function expandFrom(node, start) {
        if (!node.data.isCollapsed) return;
        node.diagram.model.setDataProperty(node.data, "isCollapsed", false);
        if (node !== start) node.diagram.model.setDataProperty(node.data, "visible", true);
        node.findNodesOutOf().each(expandFrom);
      }

      myDiagram.linkTemplate =
        $(go.Link,
          { relinkableFrom: true, relinkableTo: true, corner: 10 },
          $(go.Shape),
          $(go.Shape, { toArrow: "Standard" }));

      myDiagram.model = new go.GraphLinksModel([
        { key: "A", color: "lightgreen" },
        { key: "B1", color: "yellow" },
        { key: "B2", color: "yellow" },
        { key: "C", color: "lightblue" },
        { key: "D1", color: "orange" },
        { key: "D2", color: "orange" },
        { key: "E", color: "pink" },
        { key: "F", color: "lightgreen" },
        { key: "Z1", color: "lightgreen" },
        { key: "Z2", color: "yellow" },
        { key: "Z3", color: "orange" },
        { key: "Z4", color: "pink" }
      ], [
          { from: "A", to: "B1" },
          { from: "B1", to: "C" },
          { from: "A", to: "B2" },
          { from: "B2", to: "D2" },
          { from: "C", to: "D1" },
          { from: "C", to: "D2" },
          { from: "D1", to: "E" },
          { from: "D2", to: "E" },
          { from: "D2", to: "F" },
          { from: "Z1", to: "Z2" },
          { from: "Z2", to: "Z3" },
          { from: "Z3", to: "Z4" },
          { from: "Z4", to: "Z1" }
        ]);
    }
    window.addEventListener('DOMContentLoaded', init);
  </script>

  <div id="sample">
    <div id="myDiagramDiv" style="border: solid 1px black; width:600px; height:700px"></div>
    <p>
      The "TreeExpanderButton", which changes the <a>Node.isTreeExpanded</a> property, really only works with tree structures.
      When you want to hide/show the "downstream" nodes from a given node, using the "TreeExpanderButton" might not do what you like,
      especially when there are cycles in the graph structure.
    </p>
    <p>
      Instead, this sample implements a "Button" with custom behavior to modify the visibility of each Node.
      If this behavior is still not quite right for your app, you can adapt the behavior implemented in the
      <code>collapseFrom</code> and <code>expandFrom</code> functions to use different criteria for when to stop recursion.
    </p>
  </div>
    </div>
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